1. FIELD OF THE INVENTION
The field of this invention lies within the target and gunnery art. In particular, it lies within the specific field of aerial targets that are towed by an aircraft.
2. DESCRIPTION OF THE PRIOR ART
The prior art related to aerial gunnery targets has included those targets such as those disclosed in U.S. Pat. Nos. 2,342,651, 3,000,634, as well as other related patents that describe elongated cylindrical sleeves. In addition thereto, flat targets made from lightweight cloth have also been used and described in the prior art. The foregoing targets are generally unsatisfactory when towed at air speeds above two hundred knots. As is well known, present day aircraft activity takes place at substantially higher speeds. As a consequence, targets used for aircraft and anti-aircraft gunnery training to be effective should be capable of being towed at such speeds.
The prior art sleeves and banners that are towed have serious limitations when towed at high speeds due to the fact that they tend to flutter with increasing intensity as air speed increases. As a consequence, at certain speeds above three hundred knots, the typical banner type target will be destroyed by rapidly oscillating movement, or flapping. This is due to two reasons. First, the foregoing types of targets have a standard warp and fill thread arrangement as is common in the textile art. Thus, a vibratory mode between one elongated strand that would normally be the warp is communicated to another elongated strand through the fill threads joining them. As a consequence, the vibratory modes are transmitted between fibers. Second, when the closely woven materials that are known in the common textile art, regardless of how open the weave is, are disturbed, any region of the fabric that is not parallel to the air flow will provide an air foil type of effect, giving aerodynamic lift that will amplify the disturbance.
The invention disclosed herein provides for the elimination of transmitted forces between adjacent warp strands by substantially eliminating connecting threads or fibers such as fill fibers or other connecting elements. The target also eliminates the general characteristics of an air foil by creating small elongated strands that are roughly circular in cross section in order to minimize their lift when disturbed. As a consequence, the lift and transmittal of forces between adjacent members is greatly reduced.
The foregoing reduction of transmitted forces in adjacent members and of air foil characteristics allows the target to be towed at substantial speeds. There have been wind tunnel tests that indicate that the target of this invention can be towed at speeds commensurate with all types of high performance aircraft. As a consequence, this invention should be read broadly as a substantial step over the prior art in light of the following claims and the description of the preferred embodiments hereinafter.